1. Field of the Invention
This invention pertains generally to intrusion detection, and more particularly to intrusion detection based on ultrawideband (UWB) radar, and most particularly to intrusion detection based on UWB radar for shipping containers.
2. Description of Related Art
At a time of significant terrorist threats, the international shipping system is particularly vulnerable. It is highly desirable to improve the security of containerized cargo as it moves around the world. A goal is an improved cargo shipping container instrumented with security sensing and tracking capabilities. Any such technical capabilities implemented in the international container shipping system should maintain open borders and facilitate commerce while improving security practices by using point-of-origin security, in-transit tracking and monitoring and data query capability designed to validate and facilitate the movement of containerized cargo.
The development of a sensing and tracking system to optimize the safety of the cargo container supply chain is part of an effort by the U.S. and other countries, at various levels, and industry, to find technical solutions to enhance and secure both international and inter-modal supply chains. The effort will help to integrate the dissemination of all relevant cargo container information to the various Homeland Security components of the nations and their political subdivisions, as well as to those private sector businesses with day-to-day responsibility for tracking and transporting secure and protected cargo. Of course, the highest priority in improving cargo security is to protect against the introduction of a nuclear device or special nuclear materials into the U.S. or other countries. The development of a cargo container supply chain security system has a number of significant objectives. The system would ideally include a comprehensive sensor package (including at least intrusion sensing and radiation sensing) that can withstand environmental conditions on standard shipping routes. A near-real-time readout of container condition en-route on a secure website is desirable. It should provide a measurement of the radiation environment (as well as other environmental parameters) for the duration of standard shipping routes. A container intrusion sensor based on Ultra Wide Band (UWB) Radar technology should be included.
These components and features can be implemented in an autonomous in-container monitoring sensor system integrated with communications and information extraction equipment that is capable of continuously recording all sensor data, and detecting anomalies during transport of shipping containers. A secure web site to which sensor information can be posted for real-time viewing by designated authorities may also be part of the system. Such a system can provide timely warning of tampering to Customs and law-enforcement officials.
It is desirable that a cargo container supply chain security system (i) measures, records, and establishes environmental ground truth for future cargo monitoring system development and research, (ii) monitors the efficacy of sensors deployed to provide tampering and intrusion detection alerts and (iii) measures survivability of such systems in the complex, often harsh environments shipping containers encounter.
Wherever possible, sensors for the monitoring system should be selected to meet various criteria. The components should be commercially available. A system that is easy to operate and can be scaled cost-effectively to a large system is desirable. It is beneficial if the system enables efficient data reduction and exfiltration of information, is ruggedizable for long-life, detects and stores position, time, and sensor data while en-route, includes a Global Positioning System and is non-intrusive (will not affect normal shipping operations). Coverage of North American and Europe and extendability to other areas is desired.
A particular problem associated with the monitoring of shipping containers in transit is the possibility of false alarms. Shipping containers are subject to a lot of movement during loading, unloading, and during transit in ships and on trucks. In addition, cargo shifting inside of the container along with Radio Frequency (RF) interference must be accommodated. An effective cargo monitoring system needs to be able to discriminate against these false alarms.
One type of motion sensor applicable to this problem is based on ultrawideband (UWB) radar, as exemplified by U.S. Pat. No. 5,361,070, incorporated herein by reference. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by looking at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion. UWB motion sensors have many advantages over infrared and acoustic motion sensors, particularly in a container filled with cargo and applications where long operational lifetimes on a single battery is needed.
Accordingly it is desirable to provide an improved intrusion detection system for shipping containers. It is also desirable to provide an in-container sensor system with communications and information extraction capabilities. It is further desirable to provide a system based on UWB radar, and a system which discriminates against false alarms.